It is desirable for a dye image available from a silver halide photographic light-sensitive material not to discolor or fade even if exposed to light for a prolonged period or even when stored under the conditions of a high temperature and high humidity. Also it is desirable for a non-dye-image portion of a silver halide photographic light-sensitive material not to turn yellow (hereinafter termed "Y-stain") due to light or moisture/heat.
As a coupler for forming a magenta dye image, pyrazolone couplers, pyrazolobenzimidazole couplers, pyrazolotriazole couplers and indazolone couplers are known in the art.
However, when compared to a yellow coupler or a cyan coupler, the Y-stain in a non-dye-image portion due to moisture/heat as well as the fading in a dye-image portion due to light occur more often and in significantly larger scales, thus frequently posing a disadvantage.
The couplers widely used for forming a magenta dye are 1,2-pyrazolo-one couplers. A dye formed from a 1,2-pyrazolo-5-one magenta coupler disadvantageously has a secondary absorption in a range around 430 nm, in addition to a primary absorption in a range around 550 nm, and thus causing a great disadvantage. To solve this disadvantage, various researches have been conducted.
For instance, the magenta couplers, having an anilino group in the 3-position of 1,2-pyrazolo-5-one and disclosed for example in U.S. Pat. No. 2,343,704 and British Pat. No. 1,059,994, has a smaller secondary absorption and is accordingly useful in forming a color image for a color print.
The above-mentioned magenta couplers, however, has disadvantages. A formed image has a poor image presorvativity, and, especially, the fastness of a dye image to light is extremely poor. Also, the Y-stain in a non-dye-image portion occurs in a larger scale.
As other means to limit the secondary absorption of the above magenta couplers in a range around 430 nm, the following magenta couplers were proposed: pyrazolobenzimidazoles described in British Pat. No. 1,047,612; indazolones described in U.S. Pat. No. 3,770,447; 1H-pyrazolo[5,1-c]-1,2,4-triazole couplers described in U.S. Pat. No. 3,725,067, British Pat. Nos. 1,252,418 1,334,515; 1H-pyrazolo[1,5-b]-1,2,4-triazole couplers described in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) No. 171956/1974, and Research Disclosure No. 24,531; 1H-pyrazolo[1,5-c]-1,2,3-triazole couplers described in Research Disclosure No. 24,626; 1H-imidazo[1,2-b]-pyrazole couplers described in Japanese Patent Publication Open to Public Inspection No. 162548/1974, and Research Disclosure No. 24,531; 1H-pyrazolo[1,5-b]pyrazole couplers described in Japanese Patent O.P.I. Publication No. 43659/1985, and Research Disclosure No. 24,230; 1H-pyrazolo[1,5-d]tetrazole couplers described in Japanese Patent Publication Open to Public Inspection No. 33552/1975, and Research Disclosure No. 24,220; and others. Dyes formed especially from 1H-pyrazolo[5,1-c]-1,2,4-triazole couplers, 1H-pyrazolo[1,5-b]-1,2,4-triazole couplers, 1H-pyrazolo[ 1,5-c]-1,2,3-triazole couplers, 1H-imidazo[1,2-b]pyrazole couplers, 1H-pyrazolo[1,5-d]pyrazole couplers and 1H-pyrazolo[1,5-d]tetrazole couplers are significantly advantageous; these dyes, when compared to the previously mentioned dyes formed from 1,2-pyrazolo-5-ones which have in the 3-position an anilino group, have a significantly limited secondary absorption in a range around 430 nm, and are favorable in terms of color reproduction, and, additionally, the non-dye-image portion is least prone to subject to the Y-stain due to light, heat, or moisture.
However, azomethine dyes formed from these couplers are extremely vulnerable to light, and, worse, these dyes readily discolor due to light. Such disadvantage significantly limits the performance of a silver halide color photographic light-sensitive material especially for print. Accordingly, these couplers are not commercially used for a silver halide color photographic light-sensitive material for print.
Japanese Patent O.P.I. Publication No. 125732/1984 disclosed a proposed technique for improving light-fastness of a magenta dye image available from a 1H-pyrazolo[5,1-c]-1,2,4-triazole class magenta coupler, by using in addition to this type of coupler a phenol compound or a phenyl ether compound. This technique, however, is unsatisfactory in eliminating the fading of the magenta dye image due to light, and, it was learned that preventing light-induced discoloration is virtually impossible with this technique.